Box by pin perforating gun system and methods

Abstract

A box by pin perforating gun system using swaged down gun bodies, a removable cartridge to hold a detonator and switch, and an insulated charge holder as an electrical feed-through.

What is claimed is: 
     
       1. A perforating gun system comprising:
 a first gun body having external threads at a first end and internal threads at a second end; 
 a cartridge holding a detonator; 
 a shaped charge loading tube having an upper end and a lower end; 
 an upper end fitting on the upper end of the shaped charge loading tube; 
 a lower end fitting on the lower end of the shaped charge loading tube; 
 an upper insulating cap on upper end fitting; 
 a lower insulating cap on lower end fitting; 
 wherein the upper and lower end fittings are conductive; 
 wherein the cartridge has an electrical contact proximate to the detonator; and 
 wherein the lower end of the loading tube has an electrical contact adapted to contact the electrical contact proximate to the detonator. 
 
     
     
       2. A perforating gun system comprising:
 a first gun body having external threads at a first end and internal threads at a second end; 
 a cartridge holding a detonator; 
 a switch electrically connected to the detonator; 
 at least one insulator between the shaped charge loading tube and the gun body; 
 wherein the cartridge has at least one electrical contact at each end; and 
 wherein at least one of the electrical contacts of the cartridge is resiliently biased. 
 
     
     
       3. The perforating gun system of  claim 2  wherein at least one of the electrical contacts of the cartridge is a compression spring. 
     
     
       4. A perforating gun system comprising:
 a first gun body having external threads at a first end and internal threads at a second end; 
 a cartridge holding a detonator; 
 a switch electrically connected to the detonator; 
 at least one insulator between the shaped charge loading tube and the gun body; 
 wherein the cartridge has at least one electrical contact at each end; and 
 wherein at least one of the electrical contacts of the cartridge is a pin adapted to engage a socket in the upper end fitting of the loading tube. 
 
     
     
       5. The perforating gun system of  claim 4  wherein the socket is resiliently biased toward the pin.